1. Field of the Invention
The present invention relates to a door latch apparatus for vehicles which is constructed such that a door is prevented from opening when a vehicle is involved in a collision.
2. Description of Related Art
Generally, outside door handles are provided on outer surfaces of door panels and are used to open or close the doors. As shown in FIG. 1, a handle base plate 21 is installed in a door panel 10, and a lever 30, which is operated in conjunction with the rotation of an outside door handle 20, is coupled to the handle base plate 21 by a pin shaft 31.
The lower end of the lever 30 is connected to a door latch by a rod or cable 40. A balance weight 50 is integrally provided on the upper end of the lever 30. Furthermore, a return spring is fitted over the pin shaft 31. A first end of the return spring is fastened to the inner surface of the outside door handle 20, and a second end of the return spring is fastened to the inner surface of the balance weight 50.
The construction is such that when the outside door handle 20 is pulled, the lower end of the lever 30 is rotated in the direction corresponding to the direction in which the outside door handle 20 is pulled. Thus, the rod or cable 40, which is connected to the lower end of the lever 30, is pushed. Thereby, the door latch is unlocked, so that the door is opened.
Here, the balance weight applies an inertia load to the lever 30 in the direction opposite the direction in which the outside door handle is operated, in other words, in the direction in which the operation of the outside door handle is restricted and the latched door is prevented from being unlatched.
However, in the conventional technique in which the balance weight is provided on the outside door handle, when the outer panel of the door is deformed by an impact force F generated by a vehicle collision, the balance weight may be pushed inwards. At this time, the lower end of the lever, which is pushed inwards along with the balance weight, is rotated in the same direction as the direction in which the outside door handle is pulled during manual unlatching. Thereby, the door latch may be undesirably unlatched.
The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.